There are known arrangements which are adapted to relieve the engine load by reducing pump displacement when there is a risk for stalling the engine.
In U.S. Pat. No. 6,644,429, engine speed or engine torque is sensed and the pump displacement is reduced to zero for certain engine speed or engine torque limit values. A left and right solenoid is controlled by a controller and adapted to position the swash plates on the pumps.
In U.S. Pat. No. 4,335,577, engine speed is sensed and the pump displacement is reduced to zero for a certain engine speed limit value. The pump is short-circuited so that it regulates down; i.e., the pump output pressure is conveyed directly to the load-sensing conduit and the pressure is increased until the pump maximum pressure limitation is reached. A disadvantage is that when a higher flow is used for a function, the pump may stick on maximum displacement and cannot increase the pressure to the maximum level. The pump will then continue to pump with full flow and not maximum pressure although it is short-circuited.